fix: simplify revision diff selection into a flat list

Revisions still used ancestry lanes and placed author/date/bookmark metadata before the summary. Show short change IDs and summaries first, move metadata to a dimmed detail row, and remove the obsolete picker graph projection.

tests/unit/diff.rs

@@ -1688,75 +1688,6 @@ fn graph_state() -> DiffState {
     state
 }
 
-#[test]
-fn picker_graph_preserves_forks_merges_and_marks_filtered_ancestry() {
-    let mut state = graph_state();
-    let graph = state.picker_graph();
-    assert_eq!(graph.len(), 5);
-    assert_eq!(graph["merge"][1].trim_end(), "├─┐");
-    assert_eq!(graph["right"][1].trim_end(), "├─┘");
-    assert!(!graph.values().flatten().any(|prefix| prefix.contains('~')));
-    state.category = 1;
-    state.refilter();
-    assert_eq!(state.entries().len(), 3);
-    assert_eq!(
-        state
-            .graph_revision(state.entries().nth(1).unwrap())
-            .unwrap()
-            .0,
-        "merge"
-    );
-    assert!(matches!(
-        state.entries().nth(1).unwrap().target,
-        RevisionTarget::Bookmark { .. }
-    ));
-    state.category = 0;
-    state.query = "left root".into();
-    state.refilter();
-    assert!(state.picker_graph().is_empty());
-    assert_eq!(state.entries().len(), 1);
-    state.before = Some(state.catalog.as_ref().unwrap().entries[1].clone());
-    state.query = "right".into();
-    state.refilter();
-    assert_eq!(state.picker_graph().len(), 2);
-    assert!(state.picker_graph()["merge"][1].contains('~'));
-}
-
-#[test]
-fn graph_crossings_do_not_join_unrelated_ancestry() {
-    let mut state = DiffState::new();
-    let mut catalog = Catalog {
-        kind: RepoKind::Jujutsu,
-        entries: Vec::new(),
-        graph: Default::default(),
-        notice: None,
-    };
-    for (id, parents) in [
-        ("a", vec!["x"]),
-        ("b", vec!["y"]),
-        ("merge", vec!["x", "z"]),
-        ("x", vec![]),
-        ("y", vec![]),
-        ("z", vec![]),
-    ] {
-        catalog.entries.push(revision(
-            RevisionTarget::Commit(id.into()),
-            id,
-            "",
-            Category::Revisions,
-        ));
-        catalog.graph.insert(
-            id.into(),
-            RevisionGraph {
-                parents: parents.into_iter().map(String::from).collect(),
-                ..Default::default()
-            },
-        );
-    }
-    state.apply_result(1, Ok(Outcome::Catalog(catalog)));
-    assert_eq!(state.picker_graph()["merge"][1].trim_end(), "├─╪─┤");
-}
-
 #[test]
 fn before_identity_survives_query_and_category_without_duplicate_graph_nodes() {
     let mut state = graph_state();